The present application relates to a random number generating device, a random number generating method, and a security chip that are suitable to be applied to e.g. the case in which a spin-injection current is injected into a spin-injection magnetization reversal element to thereby generate a random number and allow this generated random number to be less readily read by an attacker.
There have been provided security chips that are allowed to have higher confidentiality through encryption of data by use of various kinds of encryption systems. For the security chip, it is required to enhance the tamper resistance to thereby prevent an attacker from reading out an encryption key stored in the chip. To meet this requirement, spin-injection magnetization reversal is increasingly employed as a technique to generate a random number used for an encryption key in a security chip and make this random number be less readily read out.
Japanese Patent Laid-open No. 2008-310403 (hereinafter, patent document 1) makes a proposal about a physical random number generating device employing a spin-injection magnetization reversal phenomenon (hereinafter, abbreviated as the “spin-injection phenomenon”) caused by injection of a spin-injection current (referred to also as the spin-polarized current) into a magnetic material. This random number generating device utilizes the characteristic that the occurrence probability of the spin-injection phenomenon is determined by the injection current based on the statistical physics as shown in J. Z. Sun, Phys. Rev. B, Vol. 62, p. 570, 2000 (hereinafter, non-patent document 1). In the random number generating device employing the spin-injection magnetization reversal, a truly random number can be generated in principle by taking advantage of this physical characteristic.
In Report on Evaluation Study about “System LSI no Security Hyouka,” Survey Commissioned by the Ministry of Economy, Trade and Industry of Japan, http://www.meti.go.jp/policy/netsecurity/downloadfiles/lsi.pdf (hereinafter, non-patent document 2), security requirements for a system LSI chip are described.